Legislation to protect the special counsel's office probe into possible Russian election interference stalled in the U.S. Senate on Wednesday, spurring Republican Senator Jeff Flake to make good on his threat of opposing judicial nominations until the bill moves forward.

Fellow Republican Vice President Mike Pence was called in as president of the Senate to break a tie vote on advancing Thomas Farr's nomination as a U.S. district judge in North Carolina, after Flake voted "no."

Flake is a strong advocate for the protection bill, known as the Special Counsel Independence and Integrity Act, which would make it harder for President Donald Trump to undermine the investigation of Russian meddling in the 2016 presidential election.